Related papers: GD 99 - an unusual, rarely observed DAV white dwar…
The pulsating hydrogen atmosphere white dwarf star G 117-B15A has been observed since 1974. Its main pulsation period at 215.19738823(63) s, observed in optical light curves, varies by only (5.12+/-0.82)x10^{-15} s/s and shows no glitches,…
We present new time-series photometry of the accreting pulsating white dwarf system GW Librae obtained in 2012 and 2013 at the University of Canterbury Mt John Observatory in New Zealand. Our 2012 data show the return of a $\sim$19 minute…
Photometric variability in massive, magnetic white dwarfs (WDs) on the timescales of less than a few hours is oft interpreted as being due to magnetic spots on the surface of a rotating star. Increasingly, numbers of these short period…
I introduce the two classes of pulsar, white-dwarf binaries, and describe for each what we have learned from a specific system, PSR J1012+5307 and PSR B0655+64, respectively, summarising what has been done, presenting new results, and…
The nature of two recently discovered radio emitters with unusually long periods of 18min (GLEAM-X J1627-52) and 21min (GPM J1839-10) is highly debated. Their bright radio emission resembles that of radio magnetars, but their long…
We make use of the high photometric precision of Kepler to search for periodic modulations among 14 normal (DA- and DB-type, likely non-magnetic) hot white dwarfs (WDs). In five, and possibly up to seven of the WDs, we detect periodic, ~2…
A surprisingly large fraction (70%) of hot, carbon dominated atmosphere (DQ) white dwarfs are magnetic and/or photometrically variable on short timescales up to ~1000 s. However, here we show that the hot DQ magnetic white dwarf SDSS…
An XMM-Mewton observation performed in May 2008 has confirmed that the 13 seconds pulsations in the X-ray binary HD 49798/RX J0648.0-4418 are due to a rapidly rotating white dwarf. From the pulse time delays induced by the 1.55 days orbital…
2MASS J05513444+4135297 (herafter J0551+4135) is the only pulsating DAQ white dwarf known with a carbon and hydrogen atmosphere. Its unusual atmospheric composition and kinematics indicate a white dwarf merger origin. We present time-series…
Hot DQ white dwarfs constitute a new class of white dwarf stars, uncovered recently within the framework of the SDSS project. Recently, three hot DQ white dwarfs have been reported to exhibit photometric variability with periods compatible…
We have investigated the nature of the magnetic white dwarf LP 790-29 = LHS 2293 by polarimetric monitoring, searching for short-term variability. No periodicity was found and we can exclude rotation periods between 4 sec and 1.5 hour with…
Axions are the natural consequence of the introduction of the Peccei-Quinn symmetry to solve the strong CP problem. All the efforts to detect such elusive particles have failed up to now. Nevertheless, it has been recently shown that the…
We report the discovery of a previously unidentified pulsar as part of a radio campaign to identify neutron star companions to low-mass white dwarfs (LMWDs) using the Robert C.\ Byrd Green Bank Telescope (GBT). PSR J0802-0955, which is…
Non-radial pulsations have been identified in a number of accreting white dwarfs in cataclysmic variables. These stars offer insight into the excitation of pulsation modes in atmospheres with mixed compositions of hydrogen, helium, and…
White dwarfs with a F, G or K type companion represent the last common ancestor for a plethora of exotic systems throughout the galaxy, though to this point very few of them have been fully characterised in terms of orbital period and…
We have used time-resolved spectroscopy to measure the colour dependence of pulsation amplitudes in the DAV white dwarf G 29-38. Model atmospheres predict that mode amplitudes should change with wavelength in a manner that depends on the…
Coherent, periodic radio emission from pulsars has been widely interpreted as evidence of neutron stars as strongly magnetized compact objects. In recent years, radio pulses have also been detected from white dwarfs (WDs) in tight binary…
A few members of the recently discovered class of long-period transients have been identified as binaries with white-dwarf primaries. In most cases, however, electromagnetic data are inconclusive, and isolated magnetars or compact binaries…
PSR J1744-3922 is a binary pulsar exhibiting highly variable pulsed radio emission. We report on a statistical multi-frequency study of the pulsed radio flux variability which suggests that this phenomenon is extrinsic to the pulsar and…
There are a few different mechanisms that can cause white dwarf stars to vary in brightness, providing opportunities to probe the physics, structures, and formation of these compact stellar remnants. The observational characteristics of the…